1. Field of the Invention
The present invention relates to continuous data protection, and more particularly, to continuously archiving data on storage devices and with preselected time intervals.
2. Background Art
Currently, there are a number of conventional methods that relate to organization of data archiving. One of these is a backup of the entire hard drive, which typically involves copying of the hard drive content onto some other medium, such as another hard disk drive, a DVD ROM, a DVD RAM, a flash disk, etc. The primary disadvantage of such a method is the need to backup what is frequently a very large amount of data, which, on the one hand, results in a relatively lengthy process of archiving, and, on the other hand, frequently requires relatively large available space for the archived data. This ultimately results in a relatively high cost of archiving per unit of archived data.
Another approach is often referred to as “incremental backup,” which generally decreases the amount of space required for the archiving. With the incremental backup, typically the content of the hard disk drive is archived, or stored somewhere once. After that, only that data that has been changed, or added, since the previous backup, or since the pervious incremental backup, is actually archived. Recovery of data from the archive typically involves merging of the original backup and the various incremental backups.
For conventional backups it is possible to restore data to the point at which the backup was taken. In case of a system failure the data can be restored from the last incremental backup. In this case, data from the time of this incremental backup creation up to time of a system failure will be lost.
On the other hand, continuous data protection is different from traditional backups. In case of a continuous data protection an initial backup is created as in case of traditional backup, but new data (which is written on the storage device) is backed up in the incremental backup (so called a continuous incremental backup, or open-for-editing incremental backup) in parallel to writing on the storage device. In other words, data is backing up to the incremental backup during the process of data writing to the storage device, but not after the passage of some time, when a user decides to make a backup of data from the data storage device.
Vcom's Autosave provides a continuous data protection. However its technology is based on file level backup and thus its system cannot be restored after a critical system failure. Block level backup provides the backing up clusters on the data storage, but not the file as a whole, so, for a block level backup, less space is necessary.
Symantec's GoBack provides a continuous data protection on the block level backup. However, GoBack uses a buffer space for storage of its change files using FIFO (First In First Out). This limits the amount of data, and, eventually, how far back is possible to go back to restore. Thus, when the buffer space becomes full, GoBack starts to delete its earlier checkpoints and storage of earlier data.
Goback's technology is based on a file level monitoring and logging technique. It needs to consume a large chunk of the hard disk space to create a history change file. The monitoring system picks up every file change, regardless of whether or not it is worth it. A simple system restart will generate hundreds of file changes to log. The details of file change history logging consumes the hard disk space quickly and puts tremendous pressure on system resources.
Accordingly, there is a need in the art for an effective and efficient method of continuous backing up data, with minimal time and effort, so data backup process allows a computer system to remain online, with possibility to restore data from the backup in the point of time forewent the system failure and in the pre-selected point of restoration.